1. Field of the Invention
The present invention relates to a liner for a gas turbine engine combustor having a trapped vortex cavity and, more particularly, to an annular cooling nugget connecting a cavity liner section with a downstream liner section.
2. Description of Related Art
Advanced aircraft gas turbine engine technology requirements are driving the combustors therein to be shorter in length, have higher performance levels over wider operating ranges, and produce lower exhaust pollutant emission levels. One example of a combustor designed to achieve these objectives is disclosed in U.S. Pat. No. 5,619,855 to Burrus. As seen therein, the Burrus combustor is able to operate efficiently at inlet air flows having a high subsonic Mach Number. This stems in part from a dome inlet module which allows air to flow freely from an upstream compressor to the combustion chamber, with fuel being injected into the flow passage. The combustor also has inner and outer liners attached to the dome inlet module which include upstream cavity portions for creating a trapped vortex of fuel and air therein, as well as downstream portions extending to the turbine nozzle.
It has been found in the aforementioned Burrus combustor that hot gases from the cavity combustion zones, having high temperatures and moderately high velocities, impinge on a corner junction where the cavity section of the respective liner joins the remaining downstream liner section. This results in high heat loads on such junction of the liner. While a cooling passage is disclosed in the '855 patent at the upstream end of the downstream liner section to initiate cooling flow along the surface thereof, additional cooling is required at both the corner junction itself and along the rear surface of the cavity liner section. Moreover, the corner junction of the cavity liner section and the downstream liner section is challenged structurally and measures which would also strengthen this area are likewise needed.
Accordingly, it would be desirable for a liner to be developed in which the junction between a cavity liner section and a downstream liner section would have greater structural stability. Further, it would be desirable if such liner would provide greater cooling at this location and along the rear portion of the cavity liner section.